Abe Lincoln Conspiracy

The Lincoln Assassination Conspiracy Trials (1865)

Military commission held in Washington, D.C., in May–June 1865 that tried eight alleged accomplices in Abraham Lincoln’s assassination (including Mary Surratt, Lewis Powell, David Herold, George Atzerodt, Samuel Mudd, Samuel Arnold, Michael O’Laughlen, and Edmund Spangler); it tested how far the federal government would stretch conspiracy law and military justice in the chaotic final weeks of the Civil War.

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Emancipation Proclamation

Lincoln’s January 1, 1863 order declaring enslaved people in rebelling states free, which transformed the Civil War into a war for emancipation, allowed Black men to join the Union army, provoked harsh Confederate retaliatory policies, and deepened the hatred men like John Wilkes Booth felt toward Lincoln and Black rights.

Knights of the Golden Circle

Secret pro-Southern organization active before and during the war; its Baltimore members were tied to early plots against Lincoln (like the 1861 assassination plan on his way to Washington), showing that conspiracies to kill him predated Booth’s scheme and that Maryland was full of Confederate sympathizers Booth later tapped.

The Pratt Street Riot

April 19, 1861 clash in Baltimore where a pro-Confederate mob attacked Massachusetts troops passing through to defend Washington, one of the first bloodshed incidents of the Civil War; it fueled fears about Maryland’s loyalty and helped justify emergency measures like suspending habeas corpus and aggressive crackdowns on dissent.

Lincoln & Habeas Corpus

Refers to Lincoln’s controversial decision (e.g., April 27, 1861 order to Winfield Scott) to suspend the writ of habeas corpus along key rail routes in Maryland so suspected rebels could be imprisoned without immediate court review, illustrating the expansion of executive power in wartime and foreshadowing the later use of military tribunals against the assassination conspirators.

Confederate Army of Manhattan

Nickname for the small team of Confederate agents who tried to burn New York City on November 25, 1864 by setting fires in hotels, a theater, and Barnum’s museum, launched from safe haven in Canada; this “black flag warfare” campaign convinced Union officials like Edwin Stanton that Confederate terror plots on Northern soil were real, shaping their interpretation of Lincoln’s murder as part of a larger Confederate conspiracy.

Sherman’s March

General William Tecumseh Sherman’s 1864–65 “March to the Sea” from Atlanta to Savannah and then through the Carolinas, destroying railroads and civilian infrastructure; it symbolized Union “total war,” contributed to Confederate collapse, and formed the military backdrop for the desperate atmosphere in which plots to kidnap or kill Lincoln intensified.

John Wilkes Booth

26-year-old famous stage actor from a notable theatrical family and a furious pro-Confederate racist who despised Lincoln, the Emancipation Proclamation, and Black suffrage; he first organized a kidnapping plot and then orchestrated the multi-pronged assassination plan against Lincoln, Seward, and (in theory) Johnson and Grant, becoming the central villain of the case.

Booth’s Kidnapping Plot

The 1864–March 17, 1865 plan by Booth and several associates (including Samuel Arnold, Michael O’Laughlen, John Surratt Jr., David Herold, George Atzerodt) to abduct Lincoln—likely on a carriage route to the Soldiers’ Home or a soldiers’ play—knock him out with chloroform, and smuggle him through Southern Maryland to Virginia to trade for Confederate POWs; its failure and partial unraveling preceded Booth’s shift to assassination and was used at trial to show a long-standing conspiracy.

Samuel Mudd

Maryland physician and slaveholder whose farm lay along the escape route; he had met Booth several times before the assassination, treated Booth’s broken leg and sheltered him and Herold early on April 15, and then tried to downplay his prior connections; the prosecution portrayed him as part of the Confederate underground and an accessory to the conspiracy, leading to his conviction by the military tribunal and life sentence at Fort Jefferson (later pardoned but never fully cleared).

John Surratt, Jr.

Mary Surratt’s son and a skilled Confederate courier who ran mail and intelligence through Southern Maryland (including to Mudd’s farm); he was involved in Booth’s earlier kidnapping plot but was out of town during the assassination, escaped to Canada and then Europe, and was later tried in a civilian court (resulting in a hung jury and dismissal on statute-of-limitations grounds), illustrating how different civilian proceedings looked once the immediate war emergency had passed.

Mary Surratt

Widowed owner of Surratt’s Tavern and a Washington, D.C. boardinghouse where Booth, Powell, Herold, and Atzerodt frequently met; accused of sending field glasses and signaling tavern keeper John Lloyd to have hidden carbines ready on April 14, she became the first woman executed by the U.S. government, and her case remains central to debates about guilt by association, gender, and the fairness of using a military tribunal for civilians.

Surratt’s Tavern

Roadside tavern in Surrattsville, Maryland (about 13 miles from D.C.), formerly run by the Surratt family and leased to John Lloyd; used as a stash site for Booth’s shotguns, carbines, ammunition, and the field glasses Mary delivered the day of the assassination, and visited by Booth and Herold as they fled, making it a key physical hub in the prosecution’s conspiracy narrative.

Surratt’s Boardinghouse

Mary Surratt’s brick boardinghouse on H Street in Washington, D.C., where she lived with her daughter and various boarders; Booth, John Surratt Jr., Lewis Powell, David Herold, and others met there repeatedly, and witness Lewis Weichmann’s testimony about those meetings and Mary’s nervous behavior helped the prosecution portray it as the conspiracy’s Washington headquarters.

George Atzerodt

German-born Confederate sympathizer and riverboatman who ferried men and contraband across the Potomac; recruited by Booth to assassinate Vice President Andrew Johnson at the Kirkwood House, he lost his nerve and never carried out the attack, but his incriminating post-arrest statements gave prosecutors important evidence about Booth’s broader plans and Samuel Mudd’s knowledge, leading to Atzerodt’s conviction and hanging.

Lewis Powell

Also known as Lewis Paine/Payne, a tall, violent former Confederate soldier and operative who was assigned to kill Secretary of State William H. Seward in a coordinated attack the night Lincoln was shot; he brutally wounded Seward and several others but failed to kill him, then was arrested after returning to the Surratt boardinghouse, making his guilt the clearest of all the defendants and helping prosecutors tie Mary Surratt’s home to active violence.

David Herold

Young pharmacy clerk and skilled woodsman from Washington who knew Southern Maryland’s terrain; helped Lewis Powell reach the Seward home and then fled in panic, later guiding Booth through swamps and safe houses as they escaped south; portrayed by his lawyer as a gullible youth under Booth’s spell, he was nonetheless convicted as a key participant and hanged by the tribunal.

Appomattox

Short for Appomattox Court House, Virginia, where Robert E. Lee surrendered the Army of Northern Virginia to Ulysses S. Grant on April 9, 1865; this near-end of the Civil War triggered massive celebrations in Washington, a more relaxed security environment around Lincoln, and increased Booth’s rage—especially after Lincoln’s April 11 speech hinting at Black suffrage—pushing him toward assassination.

Our American Cousin

Popular British-written farce being performed at Ford’s Theatre on April 14, 1865 when Lincoln attended; its structure and comedic timing (Booth chose a big laugh line to mask his shot) combined with Booth’s familiarity with the theater’s layout helped make the assassination logistically possible and shaped the iconic scene of the crime.

Lewis Weichmann & John Lloyd

Weichmann: young clerk and boarder at Mary Surratt’s house, friend of John Surratt Jr., who testified about conspirators’ meetings and Mary’s trip carrying field glasses to the tavern; Lloyd: tavern keeper who said Mary told him to have hidden carbines ready and who later served Booth and Herold that night; together, their testimony formed the backbone of the case against Mary Surratt, raising questions about credibility, self-interest, and how much weight to give accomplice-like witnesses.

Sic Semper Tyrannis

Latin phrase meaning “Thus always to tyrants,” shouted (or reputedly shouted) by Booth from the stage after shooting Lincoln and also the state motto of Virginia; it shows how Booth framed his act as tyrannicide against a “tyrant” rather than simple murder, highlighting the political and ideological nature of the crime.

Edmund Spangler

Carpenter and stagehand at Ford’s Theatre who briefly held Booth’s horse and allegedly obstructed people backstage as Booth fled; though his role was minor and evidence limited, he was swept up in the conspiracy charges, convicted of aiding Booth’s escape, and sentenced to prison, illustrating how broadly the government cast its net.

William H. Seward

Lincoln’s Secretary of State and one of the intended victims in the April 14 plot; attacked in his sickbed by Lewis Powell and severely wounded along with members of his household, Seward’s near-assassination helped prove that the plan was a coordinated attempt to decapitate Union leadership, not merely a lone madman striking at Lincoln.

Edwin Stanton

Secretary of War who rushed to the dying president’s bedside, took charge in the immediate aftermath, ordered the city sealed, directed the massive manhunt for Booth, and insisted that the suspects be tried before a military commission as “enemy belligerents”; his decisions shaped the scope of the conspiracy investigation and raised enduring questions about civil liberties versus national security in emergencies.

Federal Conspiracy Laws

Body of federal law and doctrine holding that when two or more people agree to commit a federal offense and at least one commits an overt act in furtherance of it, all members can be held criminally liable for acts done by any conspirator; in the Lincoln case, this allowed prosecutors to argue that people who never pulled a trigger (like Mary Surratt or Samuel Mudd) could still be sentenced to death or life imprisonment for being part of the alleged assassination conspiracy.

Military Trial vs. Civilian Trial

Central legal issue in the case: President Johnson, Stanton, and Judge Advocate General Holt chose a military tribunal even though regular civilian courts in Washington were open, because they cast the defendants as enemy agents in wartime; the choice meant relaxed evidence rules, no civilian jury, and limited appeals, and later Supreme Court rulings (like Milligan) would cast doubt on whether this was constitutional for civilians.

Military Tribunals and Due Process

Broad term for the tension between using military commissions to try alleged enemy agents and upholding constitutional rights like jury trial, habeas corpus, and ordinary rules of evidence; the Lincoln conspirators’ tribunal became a key example historians and lawyers use when debating how much due process is owed to suspected terrorists or enemy combatants when civil courts are functioning.

Ex Parte Vallandingham

1864 Supreme Court case involving Ohio Copperhead politician Clement Vallandigham, who was convicted by a military tribunal for anti-war speeches; the Court effectively declined to review the military conviction directly, a stance that wartime officials later cited to justify using military tribunals in the Lincoln conspiracy case.

Ex Parte Milligan

Landmark 1866 Supreme Court decision ruling that civilians in areas where civil courts are open cannot be tried by military tribunals, even in wartime; coming shortly after the Lincoln conspirators’ executions, it suggested that such commissions were unconstitutional when ordinary courts were available and became a major precedent for civil liberties.

Ex Parte Quirin

1942 Supreme Court case upholding President Roosevelt’s use of a military commission to try eight German saboteurs (including two U.S. citizens) landed by U-boats during World War II; the Court distinguished them as unlawful enemy combatants, providing a later counterpoint to Milligan and a framework that modern debates about military trials—and retrospective analysis of the Lincoln tribunal—often inv